The present invention relates to a method and an apparatus for measuring coated test panels.
For the development and quality control of coatings and painting materials, it is necessary to investigate the coatings that can be achieved therewith for various properties. For this purpose, as a rule sample coatings are produced, for which the description xe2x80x9ctest panelsxe2x80x9d has been adopted, since the article coated in the manner of a sample is often plate-shaped.
However, there are also xe2x80x9ctest panelsxe2x80x9d which are curved to different extents, for example when parts of car bodies are used or if it is precisely the coating properties in zones of curvature that are to be investigated.
The properties investigated with the aid of test panels relate to a broad spectrum of relevant properties of the coating. These include, on the one hand, the optical properties and in this case, in particular, the color properties of the coating (color, gloss, leveling, special-effect properties, haze, hiding power). On the other hand, the mechanical properties are of interest, for example such as the hardness of the coating, adhesion to the substrate and elasticity. Finally, further physical properties are of interest, such as the diffusion power of foreign substances in the layer, the electrical conductivity of the layer, the UV absorption capacity, the flame-protection effect and the durability of the layer under practical stresses. Depending on the specific task of the coating, further relevant parameters may be added. On the other hand, it may be the case that not all of the properties listed are of special significance for a specific coating or painting material, but rather that attention can be directed to a few properties.
Hitherto it has been usual to carry out the examination of test panels manually with the aid of suitable measuring devices. To this end, in the laboratory each individual test panel is examined by a worker using the appropriate measuring devices for the properties, and the measurement results are as a rule noted by hand for further evaluation. This procedure is not only very time-consuming, but furthermore is also susceptible to interference and subject to systematic errors. Thus, carrying out the measurements depends, for example, on the habits and the skill of the tester, and on account of the effort, only a few measurements, as a rule only one measurement, take place in relation to each property. Since many coating properties depend interactively (functionally) on one another, for example the hardness on the film thickness, it would be particularly important to carry out the measurements as far as possible under identical conditions, in particular at the same location on the test panel. However, in the case of the previous procedure, this is not ensured since in the case of the manual tests as a rule no attention is paid to the location of the test panel at which the measurement is carried out, and since such a location is also not able to be determined reproducible by hand with the necessary precision. The measuring methods previously used are thus time-consuming and, furthermore, subject to high errors. Finally, in the case of carrying out the tests manually, confusion may also occur if measurement data are inadvertently allocated to the wrong test panel.
An automatic measuring device is described in EP-0 383 322 A2 for biochemical analyses. In the case of this device, indicator preparations on object carriers from a supply are gripped and guided along a fixed path through the measuring device, which they finally leave at an ejection station. On their way, the indicator preparations have added to them the sample liquid to be examined, and any optical or electrochemical changes which set in are measured by an appropriate sensor. A measuring device of this type, or a comparable automatic measuring device would, however, be incapable of application or disadvantageous in the case of measuring coated test panels, since it requires a fixed geometrical format of the test panels, contains only one single type of sensor and, in particular, cannot use the (manual) measuring devices which are. usual and available.
By contrast, the object of the present invention was to provide a method and an apparatus which do not have the disadvantages outlined. The measurement of test panels is therefore to be simplified considerably and at the same time possible with higher precision and reproducibility. The method is intended to be able to change without difficulties and flexibly between various test-panel geometries and the measurements of different properties, and allocates the measurement results reliably to the measured test panels, it being in particular intended for spatially resolved measurements also to be possible. The measurements themselves are intended to be carried out with various measuring devices on a sample in a spatially resolved manner, that is to say highly precise measurements at the same-location. Furthermore, it is intended to be able to use available (manual) measuring devices.
This object is achieved by a method which comprises the following steps:
a) depositing the coated test panels in a feed station,
b) transferring a test panel from the feed station to a measuring station by means of a gripping and moving device,
c) gripping the measuring devices by means of the gripping and moving device and carrying out the measurements on the test panel in the measuring station,
d) transferring the measured test panel into a delivery station by means of the gripping and moving device.